Exact Analysis of a Linear Velocity Sensor

The velocity of a linearly moving cylindrical conductor can be measured using two methods: the laser-Doppler method and the eddy current method. In this article, we focused on an eddy current linear velocity sensor (LVS) with excellent environmental resistance while analyzing its theory to clarify its characteristics. Consequently, we were able to obtain an exact analytical solution by solving Maxwell's equation using the Fourier transform. In addition, we built an experimental apparatus that enables cylindrical conductors to move linearly and then used it to conduct an inspection experiment. As a result, a good agreement between the theory and the experiment was obtained for the speed characteristics. Therefore, we could confirm the validity of the theoretical analysis, and thus it has become possible to predict various characteristics related to LVSs. The analysis results of the theory are expected to greatly contribute to the optimization of LVSs.